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March, 03/30/2015
Events and times subject to change

March 30, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag
Federica Bianco
NYU

Echoes from the past



April 1, 2015 Wednesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


Kfir Blum
IAS

Vacuum stability bounds on Higgs coupling deviations in the absence of new bosons

Does Nature exhibit bosonic-spin particles in addition to the Standard Model Higgs and gauge bosons? Upcoming LHC data can provide a robust answer, even if the new bosonic states have masses far above direct LHC reach. To show this, we proceed by elimination and analyze the constraints imposed by Higgs vacuum stability on models with new fermions but no new bosons beyond the Standard Model. We focus on the phenomenology of Higgs couplings accessible at the LHC. New fermions that affect Higgs couplings lead to vacuum instability of the Higgs potential. Above the scale of vacuum instability, bosonic states must stabilize the potential, implying a cut-off to the pure fermion model. Conservatively tuning the models to produce the maximal cut-off for a given Higgs coupling effect, we show that observing a deviation in the Htt , H-diphoton, or H-digluon coupling, larger than 20%, would require that new bosons exist in order to stabilize the Higgs potential below about 100 TeV. For generic parameter configurations, observing a 10% deviation in any of these couplings would suggest an instability cut-off below 10-100 TeV. Similarly, if new bosons are absent up to a high scale, then a deviation in the Hbb or Hττ coupling, larger than about 20%, should be accompanied by a sizable deviation in the Zbb or Zττ couplings that can be conclusively tested with electroweak precision measurements at planned lepton colliders.


April 2, 2015 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Alessandra Lanzara
University of California, Berkeley

Switching Quantum Materials Properties with Light

The recent advancements in laser technology have dramatically expanded the applications of lasers to table top experiments in condensed matter physics. Femtosecond time-resolved spectroscopy techniques are emerging tools in the study of quantum materials, offering new paths to disentangle coexisting phases with similar energy scale, selectively tune a specific phase across a quantum critical point and create hidden states that do not exist in equilibrium, to name a few.
In this talk I will present some of our recent work where ultrafast light is used to manipulate electron charges, spin and lattice to reveal underlying properties in quantum materials, to drive metal insulator transition, to destroy superconductivity and to control spin texture in topological insulators. Future direction in the field will be discussed.


April 3, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Alan Calder
Stony Brook

Cosmic Candle Making with Thermonuclear Supernovae

Type Ia (thermonuclear) supernovae are bright stellar explosions distinguished by light curves that can be calibrated to allow for their use as "standard candles" for measuring cosmological distances. Contemporary research investigates how properties of the progenitor system that follow from properties of the host galaxy such as composition and age influence the brightness of an event. The goals are to better understand systematic effects and to assess the intrinsic scatter in the brightness, thereby reducing uncertainties in cosmological studies. We present the results from ensembles of simulations in the single-degenerate paradigm addressing the influence of age and metallicity on the brightness of an event and compare our results to observed variations of brightness that correlate with properties of the host galaxy.


April 6, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag
Alex Vikman
LMU

Imperfect Dark Matter



April 7, 2015 Tuesday 11:00 AM  +
Meyer 611
Other Physics Department Events (other)


Joshua Lui
MIT

TBA



April 8, 2015 Wednesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


Ami Katz
Boston University

TBA



April 9, 2015 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Mikhail Lukin
Harvard University

TBA



April 10, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Nikhil Padmanabhan
Yale University

The future of baryon acoustic oscillation measurements

The BAO technique is now well established as a key method to constrain the expansion history of the Universe and through it, the properties of dark energy. I will briefly review the current state of the art in BAO measurements as well as future experiments. I will also discuss some newer developments in analysis methods and how these might help address some of the challenges the next generations of surveys may face.


April 13, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag
Gabriele Veneziano
NYU



April 15, 2015 Wednesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


James Stokes
UPenn

The curious case of large-N expansions on a (pseudo)sphere



April 15, 2015 Wednesday 2:00 PM  +
Meyer 6th Floor Conference Room
Soft Condensed Matter Seminars (csmr)


Edward Lyman
University of Delaware

TBA



April 16, 2015 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Gabriel Kotliar

TBA



April 17, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Phil Marshall
Stanford

Cosmology with Strong Gravitational Lenses

Strong gravitational lenses have become an important astronomical tool: they allow us to make accurate measurements of galaxy masses, they provide a magnified view of the distant universe, and they allow us to constrain cosmological parameters. In particular, the time delays in multiply-imaged quasar systems enable measurements of distance in the Universe each with around 5% precision. I will present our recent measurement of time delay distance in two galaxy-scale lens systems. For us to realize the potential of this cosmological probe, we need to increase the size of our lens sample, and continue to improve the accuracy of its analysis. I will discuss the potential of LSST to provide a sample of several hundred lensed quasars with well-measured time delays that would enable competitive and complementary constraints on Dark Energy, and describe our ongoing investigations of how to find lenses, infer their time delays and model their mass distributions accurately, and account for weak lensing effects from external mass structures.


April 20, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag
Or Graur
NYU



April 22, 2015 Wednesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


Tony Gherghetta
University of Minnesota

TBA



April 22, 2015 Wednesday 2:00 PM  +
Meyer 6th Floor Conference Room
Soft Condensed Matter Seminars (csmr)


Garegyn Papoian

TBA



April 23, 2015 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Julio Fernandez
Columbia University

TBA



April 24, 2015 Friday 12:30 PM  +
Meyer 333
Other Physics Department Events (other)

Physics Majors' Town Hall Meeting

David Hogg, Director of Undergraduate Studies will moderate an open forum town hall meeting for Physics majors. Light refreshments will be provided.


April 24, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Daan Meerburg
CITA

Putting Inflation to the Test

We live in exciting times for cosmologists. There is a plethora of cosmological experiments that allow us to reconstruct the earliest moments in the Universe and test our ideas on how the Universe came into existence. Current data appear to favor a model that produces adiabatic, scale free, Gaussian fluctuations with an amplitude of 10^-5 in units of mK. WIthin the realm of cosmological models, it appears that such conditions are easily accomplished if we have a period of inflation driven by a single light field slowly rolling down its potential. In the first half of my talk, I will investigate the possibility to what extend our current observations would allow for a deviation from slow-roll: several class of models predicts that the fluctuation spectra will contain superimposed features on top of their slow-roll solution. I will discuss these models and explain a novel way of extract these features from the data, both in the power spectrum as well as in the bispectrum. The detection of B-mode polarization on large angular scales by the BICEP2 collaboration, and its possible primordial origin as the result of relic gravitational waves has invigorated the cosmological community. There has been much debate about the interpretation of the BICEP2 data, and this is an important issue that will be resolved with independent measurements and multi- frequency observations. The recent BICEP2/KECK and Planck 353GHz polarized map joint analysis has shown that at least a part of the BICEP2 and KECK signal is due to polarized dust. However, more importantly the observations have yielded renewed interest in constraining models of the early universe through their predictions of the spectrum of primordial gravitational waves and the testability of the inflationary scenario. One possible way to test the inflationary scenario is to verify or falsify the inflation consistency condition, which relates the amplitude of gravitational wave amplitude to its scale dependence; if tensors and scalars are sourced by the same mechanism, more power on small scales would violate the null energy condition and would suggest inflation is not responsible for the tensor modes. Much discussion has been aimed at how well we could do with future observations; In the second half of my talk I will present some results we derived from combining current data, including the latest BICEP2/KECK and Planck Polarization data. I will show that constraints from ground based gravitational wave detectors (LIGO) and pulsar timing arrays (PTA) already constrain the posterior parameter volume significantly. In addition I will show that in order to consistently use the CMB data to constrain the inflation consistency condition we should include effects of the gravitational background density on the expansion history of the Universe.


April 24, 2015 Friday 4:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


Ann Nelson
University of Washington

New Operators in Supersoft Supersymmetry Breaking and Naturalness

"Supersoft" models, with D-type supersymmetry breaking and heavy Dirac gauginos, are considerably less constrained by the LHC searches than the well studied MSSM. These models also ameliorate the supersymmetric flavor and CP problems. However, previously considered mechanisms for obtaining a natural size Higgsino mass parameter (namely, μ) in supersoft models have been relatively complicated and contrived. Obtaining 125 GeV for the mass of the lightest Higgs boson has also been difficult. Additional issues with the supersoft scenario arise from the fact that these models contain new scalars in the adjoint representation of the standard model, which may obtain negative squared-masses, breaking color and generating too large a T-parameter. However there exist new operators into supersoft models which can potentially solve all these issues. A novel feature of this framework is that the new μ-term can give unequal masses to the up and down type Higgs fields, and the Higgsinos can be much heavier than the Higgs boson without fine-tuning. Unequal Higgs and Higgsino masses destroy some theoretically attractive features of supersoft susy, but this is compensated by phenomenological virtues.


April 27, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag



April 28, 2015 Tuesday 2:00 PM  +
Meyer 611
Hard Condensed Matter Seminars (hcmp)


Efrat Shimshoni
Bar-Ilan University

Collective Edge Modes Near the Onset of a Graphene Quantum spin Hall State

Graphene subject to a strong, tilted magnetic field exhibits an insulator-metal transition tunable by tilt-angle, which is attributed to the transition from a canted antiferromagnetic (CAF) to a ferromagnetic (FM) bulk state at filling factor \nu=0. We develop a theoretical description for the spin and valley edge textures in the two phases, and the implied evolution in the nature of edge modes through the transition. In particular, we show that the CAF has gapless neutral modes in the bulk, but supports gapped charged edge modes constructed by the binding of a vortex (meron) in the bulk state to a spin twist at the edge. The energy gap of this edge mode is therefore dictated by the bulk spin stiffness. At the transition to the FM state where the latter vanishes, the charged edge modes become gapless and are smoothly connected to the helical edge modes of the FM state. We further discuss possible experimental consequences.


April 29, 2015 Wednesday 10:00 AM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

PhD defense
Daniel Foreman-Mackey
NYU

Exoplanets TBA



April 29, 2015 Wednesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


Sean Carroll
Caltech

tba



April 29, 2015 Wednesday 2:00 PM  +
Meyer 6th Floor Conference Room
Soft Condensed Matter Seminars (csmr)


Dennis Discher
University of Pennsylvania

How Long Is All The DNA in Your Body and How Do You Physically Protect It?



April 30, 2015 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Marc Kamionkowksi

TBA



May 1, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Sarbani Basu
Yale University

Journeying to the center of stars

Helioseismology, the seismic study of the Sun, has allowed us to probe the structure and dynamics of the solar interior with unprecedented accuracy. Helioseismic data have also allowed us to study properties of stellar matter. NASA's Kepler mission has allowed us to undertake seismic studies of other stars. While the field is not yet fully developed and we are still learning the best way to analyze the data, asteroseismic studies of stars has already produced exciting results. In this talk I shall review what asteroseismology is, how we interpret asteroseismic data, and then talk about some of the exciting results obtained with data from Kepler.


May 4, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag



May 6, 2015 Wednesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


Daniel Harlow
Princeton

TBA



May 7, 2015 Thursday 4:00 PM  +
Meyer 122
Physics Colloquia (colloquia)


Ivan Schuller

TBA



May 8, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Erik Tollerud
Yale University

Local Dwarf Galaxies and Near-Field Cosmology in ΛCDM

Dwarf galaxies are a frontier for new discoveries in both galaxy formation and cosmology. I will discuss work centered around connecting LCDM and its predictions to observations of dwarf galaxies at three different scales of "dwarf". I will discuss the Milky Way and M31's satellites and both solutions and lingering troubles with their abundances and scalings. I will also describe efforts to use these scalings in conjunction with simulations to constrain if and how the satellite's baryons are strongly influenced by their hosts. Finally, I will describe searches for comparable satellites beyond the Local Group, and compare their abundances and properties to straightforward LCDM expectations.


May 11, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag



May 13, 2015 Wednesday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
High Energy Physics Seminars (hep)


Kristan Jensen
Stony Brook

TBA



May 15, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Katherine Deck
Caltech

exoplanet dynamics TBD



May 18, 2015 Monday 12:30 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

CCPP Brown Bag



May 22, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Other CCPP (ccpp)

Informal Astro Talk
Lara Nava
Hebrew Univ.

GRBs and CRs



May 29, 2015 Friday 2:00 PM  +
Meyer 5th Fl. CCPP Lounge
Astrophysics and Relativity Seminars (astro)


Matthew Turk
NCSA

Astrophysical Inquiry: A Disrupted Market

The availability of low-cost hardware, high-functionality software, and the plethora of methods for acquiring, inspecting, analyzing and sharing data has changed the way individual researchers as well as entire communities -- such as astronomy and astrophysics -- understand and interact with their data. Processes that used to be hard are now trivial; processes that used to be impossible are now necessary. Drawing on examples from computational astrophysics and cosmology, I will describe how the commodity market for data-related services has changed the needs of the scientific community, and how this can be leveraged in the future to develop advanced, useful, and forward-thinking technologies to transform the way researchers interact with data.